ENERGY STAR is a joint program of the U.S. Environmental Protection Agency (EPA) and the U.S. Department of Energy (DOE).
Its mission is to help us all save money and protect the environment through energy-efficient products and practices. EPA and DOE set strict energy-efficiency guidelines for ENERGY STAR qualified products. In 2007 alone, ENERGY STAR helped Americans save more than $16 billion on their utility bills. For more information on ENERGY STAR qualified products, visit www.energystar.gov.
To become ENERGY STAR qualified, windows, doors and skylights must be independently tested and certified by the National Fenestration Rating Council and labeled according to ENERGY STAR climate zones. Manufacturers like Milgard® (an ENERGY STAR partner) tailor the components of their windows to work most efficiently where you live.
Source: ENERGY STAR U.S., ENERGY STAR Canada